U.S. patent application number 14/386568 was filed with the patent office on 2015-02-05 for electrode material for batteries, electrode material paste for batteries, method for manufacturing the electrode material for batteries, dye-sensitized solar cell, and storage battery.
The applicant listed for this patent is Kabushiki Kaisha Toshiba, Toshiba Materials Co., Ltd.. Invention is credited to Tomomichi Naka, Miho Nakamura, Akito Sasaki, Yoko Tokuno.
Application Number | 20150034149 14/386568 |
Document ID | / |
Family ID | 49259462 |
Filed Date | 2015-02-05 |
United States Patent
Application |
20150034149 |
Kind Code |
A1 |
Sasaki; Akito ; et
al. |
February 5, 2015 |
ELECTRODE MATERIAL FOR BATTERIES, ELECTRODE MATERIAL PASTE FOR
BATTERIES, METHOD FOR MANUFACTURING THE ELECTRODE MATERIAL FOR
BATTERIES, DYE-SENSITIZED SOLAR CELL, AND STORAGE BATTERY
Abstract
The present invention provides an electrode material for
batteries made from tungsten oxide powder, wherein the tungsten
oxide powder has a first peak present within a wavenumber range of
268 to 274 cm.sup.-1, a second peak present within a wavenumber
range of 630 to 720 cm.sup.-1, and a third peak present within a
wavenumber range of 800 to 810 cm.sup.-1, when a Raman
spectroscopic analysis method is performed on the electrode
material.
Inventors: |
Sasaki; Akito;
(Yokohama-Shi, JP) ; Nakamura; Miho; (Ayase,
JP) ; Naka; Tomomichi; (Chigasaki, JP) ;
Tokuno; Yoko; (Ota, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Kabushiki Kaisha Toshiba
Toshiba Materials Co., Ltd. |
Tokyo
Yokohama-Shi |
|
JP
JP |
|
|
Family ID: |
49259462 |
Appl. No.: |
14/386568 |
Filed: |
March 8, 2013 |
PCT Filed: |
March 8, 2013 |
PCT NO: |
PCT/JP2013/056485 |
371 Date: |
September 19, 2014 |
Current U.S.
Class: |
136/252 ;
252/519.32; 423/606; 428/402 |
Current CPC
Class: |
Y02E 10/542 20130101;
C01P 2002/82 20130101; H01G 9/2027 20130101; H01M 4/00 20130101;
H01G 9/2059 20130101; Y02E 60/10 20130101; Y10T 428/2982 20150115;
C01P 2006/40 20130101; H01M 4/48 20130101; C01P 2006/12 20130101;
Y02P 70/50 20151101; C01G 41/02 20130101; H01B 1/08 20130101; H01M
4/622 20130101; H01M 14/005 20130101 |
Class at
Publication: |
136/252 ;
423/606; 252/519.32; 428/402 |
International
Class: |
H01G 9/20 20060101
H01G009/20; C01G 41/02 20060101 C01G041/02; H01M 4/62 20060101
H01M004/62; H01M 4/48 20060101 H01M004/48 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 26, 2012 |
JP |
2012-069796 |
Claims
1. An electrode material for batteries made from tungsten oxide
powder, wherein the tungsten oxide powder has a first peak present
within a wavenumber range of 268 to 274 cm.sup.-1, a second peak
present within a wavenumber range of 630 to 720 cm.sup.-1, and a
third peak present within a wavenumber range of 800 to 810
cm.sup.-1, when a Raman spectroscopic analysis method is performed
on the electrode material.
2. The electrode material for batteries according to claim 1,
wherein a half-value width of the first peak is 8 to 25
cm.sup.-1.
3. The electrode material for batteries according to claim 1,
wherein a half-value width of the second peak is 15 to 75
cm.sup.-1.
4. The electrode material for batteries according to claim 1,
wherein a half-value width of the third peak is 15 to 50
cm.sup.-1.
5. The electrode material for batteries according to claim 1,
wherein a BET specific surface area of the electrode material is 15
m.sup.2/g or larger.
6. The electrode material for batteries according to claim 1,
further including a fourth peak present within a wavenumber range
of 130 to 140 cm.sup.-1, wherein the fourth peak is 0.10 or higher
in intensity ratio (I.sub.4/I.sub.3) which is a ratio of an
intensity I.sub.4 of the fourth peak to an intensity I.sub.3 of the
third peak.
7. The electrode material for batteries according to claim 1,
further including a fifth peak present within a wavenumber range of
930 to 940 cm.sup.-1, wherein the fifth peak is 0.04 or higher in
intensity ratio (I.sub.5/I.sub.3) which is a ratio of an intensity
I.sub.5 of the fifth peak to an intensity I.sub.3 of the third
peak.
8. The electrode material for batteries according to claim 1,
wherein the electrode material is used in a dye-sensitized solar
cell or a storage battery.
9. An electrode material paste for batteries, including an
electrode material for batteries according to claim 1.
10. The electrode material paste for batteries according to claim
9, including a binder whose pyrolysis rate at 500.degree. C. is
99.0% or higher.
11. The electrode material paste for batteries according to claim
9, wherein the electrode material paste has a viscosity of 800 to
10000 cps.
12. A method for manufacturing an electrode material for batteries
according to claim 1, the method comprising: a step of preparing
metallic tungsten powder or tungsten compound powder; and a plasma
treatment step of plasma-treating the metallic tungsten powder or
the tungsten compound powder in an oxygen-containing ambient
atmosphere.
13. The method for manufacturing an electrode material for
batteries according to claim 12, the method further comprising a
heat treatment step of performing a heat treatment at 300 to
1000.degree. C. in an oxygen-containing ambient atmosphere,
following the plasma treatment step.
14. The method for manufacturing an electrode material for
batteries according to claim 13, wherein the heat treatment step is
a step in which one type of treatment selected from among heat
treatment in atmosphere, heat treatment in a pressurized ambient
atmosphere, heat treatment in water, and microwave heat treatment,
is performed.
15. A dye-sensitized solar cell using an electrode material for
batteries according to claim 1.
16. A storage battery using an electrode material for batteries
according to claim 1.
Description
TECHNICAL FIELD
[0001] The present invention relates to an electrode material for
batteries, an electrode material paste for batteries, a method for
manufacturing the electrode material for batteries, a
dye-sensitized solar cell, and a storage battery.
BACKGROUND ART
[0002] In recent years, solar cells for which solar energy
available as natural energy can be utilized have been a focus of
attention.
[0003] Initially, a silicon-based solar cell has been used mainly
as the solar cell. The silicon-based solar cell has the advantage
of being able to achieve a power generation efficiency of no less
than 10%.
[0004] Vacuum film-forming techniques, such as the crystal growth
of silicon and sputtering, are frequently used, however, in order
to manufacture the silicon-based solar cell. Accordingly, the
silicon-based solar cell is high in manufacturing cost.
[0005] Hence, as a technology in which the manufacturing cost of
solar cells is decreased, studies are being made of a
dye-sensitized solar cell formed by fixating a light-absorbing dye
on the surfaces of fine particles of a semiconductor other than
silicon. This dye-sensitized solar cell is fabricated by fixating a
dye on the surfaces of semiconductor fine particles. Accordingly,
paste coating techniques are frequently used in the fabrication of
the dye-sensitized solar cell.
[0006] For example, Patent Document 1 (Japanese Patent Laid-Open
No. 2008-204956) describes that a specific degree of power
generation efficiency can be attained by using titanium oxide
powder as an electrode material and fixating a dye on the particle
surfaces of this titanium oxide powder. According to the technique
described in Patent Document 1, it is possible to reduce
manufacturing costs.
[0007] Since a solar cell literally uses solar light, the amount of
electrical generation varies depending on the amount of solar
insolation. Accordingly, the solar cell has been problematic in
that if the amount of solar insolation drastically decreases, as in
the case of, for example, the solar cell being moved from an
outdoor location into an indoor location during daytime hours, the
amount of electrical generation drastically decreases as well.
[0008] As a technology to cope with such a change in the amount of
solar insolation, Patent Document 2 (Japanese Patent Laid-Open No.
2009-135025) describes a technique of providing a dye-sensitized
solar cell with an electricity storage function by disposing a
solid electricity storage layer on a photoelectric conversion
layer.
PRIOR ART DOCUMENTS
Patent Documents
[0009] Patent Document 1: Japanese Patent Laid-Open No. 2008-204956
[0010] Patent Document 2: Japanese Patent Laid-Open No.
2009-135025
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
[0011] It is difficult, however, to satisfy both of power
generation efficiency and electricity storage efficiency at a high
level simply by laminating the solar cell with two layers, i.e.,
the photoelectric conversion layer and the solid electricity
storage layer, as described in Patent Document 2. What is important
for the effective use of solar light is to improve electricity
storage efficiency.
[0012] An object of the present invention, which has been
accomplished in view of the above-described circumstances, is to
provide an electrode material for batteries high in electricity
storage efficiency, electrode material paste for batteries
comprising this electrode material for batteries, a method for
manufacturing the electrode material for batteries, a
dye-sensitized solar cell using the electrode material for
batteries, and a storage battery.
Means for Solving the Problems
[0013] The present invention has been accomplished by finding out
that tungsten oxide powder the characteristics of which measured by
a Raman spectroscopic analysis method are within a determinable
range is high in electricity storage efficiency.
[0014] An electrode material for batteries of the present
invention, which is intended to solve the above-described problem,
is an electrode material for batteries made from tungsten oxide
powder, and the tungsten oxide powder has a first peak present
within a wavenumber range of 268 to 274 cm.sup.-1, a second peak
present within a wavenumber range of 630 to 720 cm.sup.-1, and a
third peak present within a wavenumber range of 800 to 810
cm.sup.-1, when a Raman spectroscopic analysis method is performed
on the electrode material.
[0015] In addition, an electrode material paste for batteries,
which is intended to solve the above-described problem, contains
the electrode material for batteries.
[0016] Yet additionally, a method for manufacturing the electrode
material for batteries of the present invention, which is intended
to solve the above-described problem, is a method for manufacturing
the above-described electrode material for batteries and comprises:
a step of preparing metallic tungsten powder or tungsten compound
powder; and a plasma treatment step of plasma-treating the metallic
tungsten powder or the tungsten compound powder in an
oxygen-containing ambient atmosphere.
[0017] Still additionally, a dye-sensitized solar cell of the
present invention, which is intended to solve the above-described
problem, uses the above electrode material for batteries.
[0018] Still additionally, a storage battery of the present
invention, which is intended to solve the above-described problem,
uses the electrode material for batteries.
Advantages of the Invention
[0019] The electrode material for batteries, the dye-sensitized
solar cell and the storage battery of the present invention are
high in electricity storage efficiency.
[0020] According to the electrode material for batteries, the
electrode material paste for batteries, and the method for
manufacturing the electrode material for batteries of the present
invention, it is possible to manufacture an electrode material for
batteries, a dye-sensitized solar cell, and a storage battery high
in electricity storage efficiency.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is a cross-sectional view showing a first embodiment
of a dye-sensitized solar cell of the present invention.
[0022] FIG. 2 is a cross-sectional view showing a second embodiment
of a dye-sensitized solar cell of the present invention.
[0023] FIG. 3 is a cross-sectional view showing a storage battery
of the present invention.
[0024] FIG. 4 illustrates measurement results based on Raman
spectroscopic analysis.
DESCRIPTION OF EMBODIMENTS
Electrode Material for Batteries
[0025] The electrode material for batteries of the present
invention is composed of tungsten oxide (WO.sub.3) powder. Tungsten
oxide powder which is the electrode material for batteries of the
present invention has at least the first peak, the second peak and
the third peak to be described below when a Raman spectroscopic
analysis method is performed on the tungsten oxide powder. The
electrode material for batteries of the present invention is high
in electricity storage efficiency if the electrode material has at
least the first peak, the second peak and the third peak to be
described below.
[0026] As the measuring conditions of the Raman spectroscopic
analysis method, the peaks are measured by using, for example, a
microscopic laser Raman spectral device, setting the measurement
mode thereof to "Microscopic Raman", and using an Ar.sup.+ laser
having a wavelength of 514.5 nm as a light source. As the
microscopic laser Raman spectral device, it is possible to use, for
example, PDP-320 made by Photon Design Corporation.
(First Peak)
[0027] The first peak is a peak present within the wavenumber range
of 268 to 274 cm.sup.-1.
[0028] A half-value width (half band width) of the first peak is
normally 8 to 25 cm.sup.-1, and preferably 12 to 18 cm.sup.-1.
[0029] If the half-value width of the first peak is less than 8
cm.sup.-1, the electricity storage efficiency of the electrode
material for batteries of the present invention is liable to be
low.
[0030] If the half-value width of the first peak exceeds 25
cm.sup.-1, the electrode material for batteries of the present
invention is liable to agglutinate and, consequently, degrade in
electricity storage efficiency.
(Second Peak)
[0031] The second peak is a peak present within the wavenumber
range of 630 to 720 cm.sup.-1.
[0032] A half-value width of the second peak is normally 15 to 75
cm.sup.-1, and preferably 15 to 40 cm.sup.-1.
[0033] If the half-value width of the second peak is less than 15
cm.sup.-1, the electricity storage efficiency of the electrode
material for batteries of the present invention is liable to be
low.
[0034] If the half-value width of the second peak exceeds 75
cm.sup.-1, the electrode material for batteries of the present
invention is liable to agglutinate and, consequently, degrade in
electricity storage efficiency.
(Third Peak)
[0035] The third peak is a peak present within the wavenumber range
of 800 to 810 cm.sup.-1.
[0036] A half-value width of the third peak is normally 15 to 50
cm.sup.-1, and preferably 15 to 30 cm.sup.-1.
[0037] If the half-value width of the third peak is less than 15
cm.sup.-1, the electricity storage efficiency of the electrode
material for batteries of the present invention is liable to be
low.
[0038] If the half-value width of the third peak exceeds 50
cm.sup.-1, the electrode material for batteries of the present
invention is liable to agglutinate and, consequently, degrade in
electricity storage efficiency.
[0039] The tungsten oxide powder which is the electrode material
for batteries of the present invention preferably further has the
fourth peak or the fifth peak to be described below, in addition to
the above-described first peak, second peak and third peak, when a
Raman spectroscopic analysis method is performed on the tungsten
oxide powder.
(Fourth Peak)
[0040] The fourth peak is a peak present within the wavenumber
range of 130 to 140 cm.sup.-1.
[0041] The fourth peak is normally 0.10 or higher, preferably 0.12
to 0.3, and even more preferably 0.17 to 0.3 in intensity ratio
(I.sub.4/I.sub.3) which is the ratio of the intensity I.sub.4 of
the fourth peak to the intensity I.sub.3 of the third peak.
[0042] The intensity ratio (I.sub.4/I.sub.3) is preferably 0.10 or
higher, since both the electricity storage efficiency and power
generation efficiency of tungsten oxide powder which is the
electrode material for batteries upgrade when a dye is fixated on
the particle surfaces of the tungsten oxide powder. Using tungsten
oxide powder as an electrode material for batteries in a storage
battery to be described later is effective in also increasing
electricity storage capacity to 1500 C/m.sup.2 or higher.
[0043] The tungsten oxide powder which is the electrode material
for batteries of the present invention is produced after being made
to go through at least a plasma treatment step, as will be
described later. The tungsten oxide powder which is the electrode
material for batteries of the present invention is produced by
further carrying out a rapid cooling step or a heat treatment step,
as necessary, following the plasma treatment step.
[0044] Among the types of tungsten oxide powder which is the
electrode material for batteries of the present invention, tungsten
oxide powder the intensity ratio (I.sub.4/I.sub.3) of which is 0.10
or higher and which is high in both electricity storage efficiency
and power generation efficiency when a dye is fixated on the
particle surfaces of the tungsten oxide powder can generally be
produced by carrying out at least a heat treatment step following
the plasma treatment step.
(Fifth Peak)
[0045] The fifth peak is a peak present within the wavenumber range
of 930 to 940 cm.sup.-1.
[0046] The fifth peak is normally 0.04 or higher in intensity ratio
(I.sub.5/I.sub.3) which is the ratio of the intensity I.sub.5 of
the fifth peak to the intensity I.sub.3 of the third peak.
[0047] The intensity ratio (I.sub.5/I.sub.3) is preferably 0.04 or
higher, since the tungsten oxide powder which is the electrode
material for batteries is particularly high in electricity storage
efficiency. This intensity ratio is particularly effective in
obtaining a storage battery having electricity storage capacity
lower than 1500 C/m.sup.2.
[0048] Among the types of tungsten oxide powder which is the
electrode material for batteries of the present invention, tungsten
oxide powder the intensity ratio (I.sub.5/I.sub.3) of which is 0.04
or higher and which is particularly high in electricity storage
efficiency can generally be produced by not carrying out a heat
treatment step following the plasma treatment step.
(BET Specific Surface Area)
[0049] The tungsten oxide (WO.sub.3) powder which is the electrode
material for batteries of the present invention is normally 15
m.sup.2/g or larger, and preferably 20 to 150 m.sup.2/g in BET
specific surface area.
[0050] Tungsten oxide powder having a BET specific surface area of
15 m.sup.2/g or larger is high in electricity storage
efficiency.
(Advantageous Effects of Electrode Material for Batteries)
[0051] The tungsten oxide powder which is the electrode material
for batteries of the present invention is high in electricity
storage efficiency. According to the tungsten oxide powder which is
the electrode material for batteries of the present invention, it
is therefore possible to obtain a dye-sensitized solar cell or a
storage battery having high electricity storage efficiency.
[Method for Manufacturing Electrode Material for Batteries]
[0052] Next, a description will be made of a method for
manufacturing the electrode material for batteries of the present
invention. The method for manufacturing the electrode material for
batteries of the present invention comprises at least a plasma
treatment step.
(Plasma Treatment Step)
[0053] The plasma treatment step is a step of plasma-treating
metallic tungsten powder or tungsten compound powder in an
oxygen-containing ambient atmosphere.
[0054] Specifically, the plasma treatment step is a step of
sublimating metallic tungsten powder or tungsten compound powder
which is a raw material by plasma treatment in an oxygen-containing
ambient atmosphere.
[0055] In the plasma treatment step, sublimation by plasma
treatment is performed in an oxygen ambient atmosphere. Metallic
tungsten powder or tungsten compound powder is thus instantaneously
sublimated to generate gas-phase metallic tungsten vapor from the
solid-phase powder. This metallic tungsten vapor is oxidized to
obtain fine tungsten oxide (WO.sub.3) powder. The fine tungsten
oxide (WO.sub.3) powder is available since gas-phase oxidation
reaction is utilized.
<Metallic Tungsten Powder and Tungsten Compound Powder>
[0056] As metallic tungsten powder for use in the plasma treatment
step, powdery metallic tungsten is used. As tungsten compound
powder for use in the plasma treatment step, tungsten oxide, such
as tungsten trioxide (WO.sub.3) or tungsten dioxide (WO.sub.2),
tungsten carbide, ammonium tungstate, calcium tungstate, or
tungsten acid, for example, is used.
[0057] A raw material used in the plasma treatment step is
preferably metallic tungsten powder, tungsten trioxide powder,
tungsten carbide powder or ammonium tungstate powder. If metallic
tungsten powder, tungsten trioxide powder, tungsten carbide powder
or ammonium tungstate powder is used as the raw material, tungsten
trioxide powder obtained after the raw material is sublimated in an
oxygen ambient atmosphere is less likely to contain impurities. In
addition, in the case of metallic tungsten powder, tungsten
trioxide powder and tungsten carbide powder, any harmful substances
are less likely to be formed as by-products, i.e., substances other
than tungsten trioxide, formed after a sublimation step.
[0058] Metallic tungsten powder or tungsten compound powder which
is the raw material used in the plasma treatment step has an
average particle diameter D.sub.50 of 10 .mu.m or smaller, and
preferably 1 to 5 .mu.m.
[0059] If the average particle diameter D.sub.50 of metallic
tungsten powder or tungsten compound powder serving as the raw
material exceeds 10 .mu.m, it becomes difficult to uniformly feed
the metallic tungsten powder or the tungsten compound powder into
plasma flame. Accordingly, a uniform plasma treatment is not
feasible, and therefore, a variation (scattering) is liable to
occur in the particle diameter of tungsten oxide (WO.sub.3) powder
obtained after the plasma treatment step.
[0060] On the other hand, if the average particle diameter D.sub.50
of metallic tungsten powder or tungsten compound powder serving as
the raw material is smaller than 1 .mu.m, it is difficult to
prepare the metallic tungsten powder or the tungsten compound
powder. Accordingly, the manufacturing cost of the electrode
material tends to be high.
<Plasma Treatment>
[0061] As the plasma treatment, an inductively-coupled plasma
treatment, for example, is used. The inductively-coupled plasma
treatment is preferred since a large amount of raw material powder
is oxidized at a time in an oxygen ambient atmosphere, and
therefore, a large amount of tungsten oxide (WO.sub.3) powder can
be easily obtained at a time. This is because in a plasma treatment
such as the inductively-coupled plasma treatment, the amount of raw
material that can be treated at a time can be controlled by
adjusting the area of plasma generation.
[0062] In the plasma treatment, a method is used generally in which
plasma is generated in an oxygen ambient atmosphere composed of
argon and oxygen gases, and then metallic tungsten powder or
tungsten compound powder is supplied into this plasma.
[0063] As a method for supplying metallic tungsten powder or
tungsten compound powder into plasma, a method is used, for
example, in which metallic tungsten powder or tungsten compound
powder is blown into the plasma along with a carrier gas, or a
method in which a dispersion liquid prepared by dispersing metallic
tungsten powder or tungsten compound powder in a predetermined
liquid dispersion medium is blown into the plasma.
[0064] Examples of the carrier gas used in the method for blowing
metallic tungsten powder or tungsten compound powder into the
plasma may include air, oxygen, and an oxygen-containing inert gas.
Among the examples, air is preferred since it is low-cost. If
oxygen is sufficiently contained in a reaction field as in cases
where an oxygen-containing reactant gas is flowed in addition to
the carrier gas or the tungsten compound powder is made from
tungsten trioxide, an inert gas, such as argon or helium, may be
used as the carrier gas.
[0065] In a case where the method for blowing in the dispersion
liquid prepared by dispersing metallic tungsten powder or tungsten
compound powder into the predetermined liquid dispersion medium is
adopted, a liquid dispersion medium containing oxygen atoms in the
molecule is used as the dispersion medium for use in the production
of a dispersion liquid composed of metallic tungsten powder or
tungsten compound powder. Use of the dispersion liquid is preferred
since raw material powder is easy to handle. As the liquid
dispersion medium containing oxygen atoms in the molecule, a
dispersion medium containing 20% by volume or more of at least one
of water and alcohol, for example, is used.
[0066] As alcohol for use in the liquid dispersion medium, at least
one type of alcohol selected from the group consisting of methanol,
ethanol, 1-propanol and 2-propanol is used. Water and alcohol are
preferred since they do not disturb the sublimation and oxidation
reactions of raw material powder as they are easily vaporized by
the heat of plasma, and since they easily facilitate oxidation
reactions as they contain oxygen in their molecules.
[0067] The center temperature of plasma flame used in the plasma
treatment is normally set to 8000.degree. C. or higher, and
preferably 10000.degree. C. or higher. Use of high-temperature
plasma flame having a center temperature of 8000.degree. C. or
higher is preferred since tungsten oxide (WO.sub.3) powder obtained
becomes fine.
[0068] In the plasma treatment step, tungsten oxide (WO.sub.3)
powder is obtained as the result of metallic tungsten vapor
generated by sublimating metallic tungsten in plasma flame being
oxidized by oxygen in an oxygen ambient atmosphere. Thus obtained
the tungsten oxide (WO.sub.3) powder flies out of plasma flame.
Tungsten oxide (WO.sub.3) powder having flown out of plasma flame
may be left to cool. In the method for manufacturing the electrode
material for batteries of the present invention, however, it is
preferable to carry out a rapid cooling step of rapidly cooling the
tungsten oxide (WO.sub.3) powder having flown out of plasma flame.
That is, the rapid cooling step is preferably carried out following
the plasma treatment step in the method for manufacturing the
electrode material for batteries of the present invention.
(Rapid Cooling Step)
[0069] A rapid cooling step is a step of rapidly cooling tungsten
oxide (WO.sub.3) powder obtained in a plasma treatment step and
having flown out of plasma flame.
[0070] Carrying out the rapid cooling step following the plasma
treatment step makes it easy for the obtained tungsten oxide
(WO.sub.3) powder to be high in electricity storage efficiency.
[0071] The rapid cooling treatment of the rapid cooling step is
performed in a rapid cooling area located between a surface of
plasma flame and a surface away at a predetermined distance from
this surface. The rapid cooling area is provided so that a rapid
cooling distance which is a distance at which tungsten oxide
(WO.sub.3) powder flying out of plasma flame is rapidly cooled is
normally 1 m or longer, and preferably 1.5 to 2 m.
[0072] The rapid cooling area is set so that the cooling rate of
tungsten oxide (WO.sub.3) powder flying out of plasma flame is
1000.degree. C./s or higher.
[0073] In the method for manufacturing the electrode material for
batteries of the present invention, a heat treatment step is
preferably further carried out following the plasma treatment step
or the rapid cooling step.
(Heat Treatment Step)
[0074] A heat treatment step is a step of performing a heat
treatment at 300 to 1000.degree. C. in an oxygen-containing ambient
atmosphere, following the plasma treatment step. If the rapid
cooling step is carried out following the plasma treatment step,
the heat treatment step is carried out following the rapid cooling
step.
[0075] Tungsten oxide (WO.sub.3) powder (hereinafter referred to as
"non-heat treated tungsten oxide (WO.sub.3) powder") obtained by
carrying out a plasma treatment step or a rapid cooling step is
liable to contain many lattice defects in particle surfaces, and
therefore, tends to contain powder of tungsten oxide other than
WO.sub.3. Here, examples of tungsten oxide other than WO.sub.3 may
include WO.sub.2 and W.sub.2O.sub.3 in which y/x of W.sub.xO.sub.y
is normally smaller than 3.
[0076] Carrying out a heat treatment step reduces or eliminates
lattice defects in the surfaces of obtained tungsten oxide
(WO.sub.3) powder and upgrades the purity thereof to, for example,
99% or higher. In addition, carrying out a heat treatment step
places the crystal structure and the particle diameter of WO.sub.3
of obtained tungsten oxide (WO.sub.3) powder in a state suited to
improve power generation efficiency when a dye is fixated on the
particle surfaces of the tungsten oxide powder. Accordingly,
tungsten oxide (WO.sub.3) powder obtained by carrying out a heat
treatment step is high in power generation efficiency when a dye is
fixated on the surfaces of the tungsten oxide powder, in addition
to being high in electricity storage efficiency.
[0077] As the oxygen-containing ambient atmosphere, oxygen,
atmospheric air, an inert gas in which water vapor or oxygen is
introduced, or water, for example, is used. If the
oxygen-containing ambient atmosphere is water, a heat treatment is
performed in water. The pressure of the ambient atmosphere is not
limited in particular, but is normally atmospheric pressure or
higher.
[0078] A heat treatment is performed so that the maximum
temperature of the non-heat treated tungsten oxide (WO.sub.3)
powder becomes normally 300 to 1000.degree. C., and preferably 450
to 600.degree. C.
[0079] The time of retaining the maximum temperature in the heat
treatment is set to normally 10 minutes or longer, preferably 1 to
60 hours, and more preferably 2 to 60 hours.
[0080] If the maximum temperature of the heat treatment and the
retention time of retaining the maximum temperature are within the
abovementioned ranges, non-heat treated tungsten oxide (WO.sub.3)
powder is slowly oxidized in a temperature region low in oxidation
reaction rate, thus eliminating lattice defects present in the
surfaces and interiors of the tungsten oxide powder. This makes it
easy to obtain tungsten oxide (WO.sub.3) powder high in both
electricity storage efficiency and power generation efficiency when
a dye is fixated on the particle surfaces of the tungsten oxide
powder.
[0081] The particle diameter of the non-heat treated tungsten oxide
(WO.sub.3) powder can be made all the smaller since no heat is
applied thereto. Since decreasing the particle diameter of the
WO.sub.3 powder increases the surface area thereof, it is possible
to increase the area of the powder to have contact with an
electrolytic solution. On the other hand, lattice defects present
in the surfaces and interiors of the WO.sub.3 powder remain intact
since no heat is applied thereto. The lattice defects, if left
over, serve as internal resistance, and therefore, electricity
storage efficiency may not improve any further. The lattice defects
have significant adverse effects, in particular, when the thickness
of a semiconductor layer is increased to raise electricity storage
capacity. Accordingly, the tungsten oxide powder is preferably not
heat-treated when used in a storage battery having electricity
storage capacity lower than 1500 C/m.sup.2, and is preferably
heat-treated when used in a storage battery having electricity
storage capacity no lower than 1500 C/m.sup.2.
[0082] If the maximum temperature of the heat treatment is too
high, a reaction rate is high at surface sites of the tungsten
oxide powder, and therefore, the degree of elimination of lattice
defects tends to differ for each particle of non-heat treated
tungsten oxide (WO.sub.3) powder. Consequently, lattice defects
present in surfaces and interiors of particles are liable to remain
intact in tungsten oxide (WO.sub.3) powder obtained after the heat
treatment. Too high a maximum temperature is therefore not
preferable.
[0083] If the maximum temperature of the heat treatment exceeds
1000.degree. C. in particular, WO.sub.3 particles exhibit drastic
particle growth, thus causing a variation in the diameter of
particles. Consequently, it is difficult to obtain tungsten oxide
(WO.sub.3) powder high in both electricity storage efficiency and
power generation efficiency when a dye is fixated on the particle
surfaces of the tungsten oxide powder.
[0084] The heat treatment is performed by means of, for example,
atmosphere thermal conduction, radiation heat, high-frequency
irradiation, microwave irradiation, or laser light irradiation. A
heat treatment by means of radiation heat is performed using, for
example, an electric furnace.
[0085] Preferred examples of the heat treatment in the heat
treatment step are a heat treatment in the atmosphere, a heat
treatment in a pressurized ambient atmosphere, a heat treatment in
water, and a microwave heat treatment. That is, the heat treatment
step is preferably a step in which one type of treatment selected
from the group consisting of a heat treatment in the atmosphere, a
heat treatment in a pressurized ambient atmosphere, a heat
treatment in water, and a microwave heat treatment is
performed.
[0086] The heat treatment in the atmosphere is a heat treatment
performed in the atmosphere, and is performed using, for example,
an electric furnace in which atmospheric air is introduced into a
chamber.
[0087] The heat treatment in a pressurized ambient atmosphere is a
heat treatment performed in a pressurized ambient atmosphere, and
is performed using, for example, an electric furnace in which the
inner side of a chamber is set to a pressurized ambient
atmosphere.
[0088] The heat treatment in water is a heat treatment performed
with the non-heat treated tungsten oxide (WO.sub.3) powder which is
an object of the heat treatment dispersed in water, and is
performed by means of, for example, the irradiation of
high-frequency waves, microwaves, or laser light.
[0089] The microwave heat treatment is performed using, for
example, a microwave heating device.
[0090] Carrying out the above-described steps can provide tungsten
oxide (WO.sub.3) powder which is the electrode material for
batteries of the present invention.
(Advantageous Effects of Method for Manufacturing Electrode
Material for Batteries)
[0091] According to the method for manufacturing the electrode
material for batteries of the present invention, it is possible to
efficiently manufacture tungsten oxide powder which is the
electrode material for batteries of the present invention.
[Electrode Material Paste for Batteries]
[0092] The electrode material paste for batteries of the present
invention contains the electrode material for batteries of the
present invention.
[0093] Specifically, the electrode material paste for batteries of
the present invention contains the electrode material for batteries
of the present invention, a binder, and a solvent.
[0094] As the binder, a binder the pyrolysis rate of which at
500.degree. C. is, for example, 99.0% or higher is used. A binder
having a pyrolysis rate of 99.0% or higher at 500.degree. C. is
preferred since damage is less likely to be caused to a substrate,
such as a glass substrate, when the electrode material paste for
batteries is coated on the substrate. Here, a pyrolysis rate at
500.degree. C. means a pyrolysis rate when the binder is
heat-treated at 500.degree. C. for 30 minutes. The symbol % in
pyrolysis rates refers to percent by mass.
[0095] The electrode material paste for batteries coated on a
substrate, such as a glass substrate, is heating-treated to remove
the binder and the solvent. Consequently, the electrode material
for batteries is attached firmly onto the substrate. At this time,
if the temperature of the heating treatment is too high, damage is
liable to occur because, for example, the substrate, such as a
glass substrate, may turn soft and become deformed or the
properties of the material may change. If a binder having a
pyrolysis rate of 99.0% or higher at 500.degree. C. is used, damage
such as deformation or property variation, is less likely to be
caused to the substrate, such as a glass substrate.
[0096] As the binder having a pyrolysis rate of 99.0% or higher at
500.degree. C., ethyl cellulose or polyethylene glycol, for
example, is used.
[0097] As the solvent, alcohol, an organic solvent, or pure water,
for example, is used. Among them, an alcohol-based solvent is
preferred. Among alcohol-based solvents, terpineol is
preferred.
[0098] Assuming that the total amount of the electrode material for
batteries, the binder and the solvent is 100% by mass, the
electrode material paste for batteries is normally 5 to 50% by
mass, preferably 20 to 40% by mass, and more preferably 30 to 40%
by mass in the blending ratio of the electrode material.
[0099] If the blending ratio of the electrode material for
batteries in the electrode material paste for batteries is 5 to 50%
by mass, the electrode material paste for batteries is superior in
handleability.
[0100] When calculating the blending ratio of the electrode
material for batteries in the electrode material paste for
batteries, the ingredient amount of the electrode material for
batteries is generally calculated from the mass of tungsten oxide
alone. If any additive adheres to surfaces of powder particles made
from tungsten oxide or any coating film is formed on the surfaces,
however, the mass of the electrode material including the additive
and the coating film should be adjusted to within the
abovementioned range.
[0101] Assuming that the total amount of the electrode material for
batteries, the binder and the solvent is 100% by mass, the
electrode material paste for batteries is normally 3 to 30% by
mass, preferably 4 to 20% by mass, and more preferably 4 to 10% by
mass in the blending ratio of the binder.
[0102] The electrode material paste for batteries is normally 800
to 10000 cps, and preferably 3000 to 7000 cps in viscosity at
25.degree. C.
[0103] The electrode material paste for batteries is prepared by
mixing the electrode material for batteries, the binder and the
solvent.
[0104] As the order of mixing (blending), it is generally
preferable to mix the binder and the solvent first, and then add
the electrode material for batteries. It is not preferable to mix
the electrode material for batteries, the binder and the solvent at
one time since many aggregates are contained in the electrode
material paste for batteries thus obtained.
[0105] It is preferable to sufficiently agitate (stir) the binder
and the solvent when mixing the binder and the solvent and adding
the electrode material for batteries. The reason for this is that
insufficient agitation gives rise to aggregates since the electrode
material for batteries of the present invention is powder made of
fine particles having a BET specific surface area of 15 m.sup.2/g
or larger.
[0106] The electrode material paste for batteries is coated on a
surface of a transparent conductive film, electrode, electricity
generation layer or the like formed on a surface of, for example, a
glass substrate using a screen printing method or the like, and
then calcinated (baked) at a temperature of 500.degree. C. or
lower. As the result of this calcination, the binder and the
solvent contained in the electrode material paste for batteries are
removed or decomposed and the particles of the electrode material
for batteries firmly bond to one another, thus forming an
electricity storage layer composed of the electrode material for
batteries.
[0107] Here, the electricity generation layer refers to a layer
which generates electricity when exposed to the irradiation of
light, such as solar light. The electricity generation layer is a
layer composed of, for example, an anchoring structure formed as
the result of the particles of a photoelectric conversion material
being firmly bonded to one another due to necking or the like.
Here, the photoelectric conversion material refers to a material
having photoelectric conversion properties. As the photoelectric
conversion material, there is used at least one type of material
selected from the group consisting of, for example, titanium oxide,
tin oxide, tungsten oxide, zinc oxide, zirconium dioxide, neodymium
oxide, hafnium oxide, strontium oxide, indium oxide, cerium oxide,
yttrium oxide, lanthanum oxide, vanadium oxide, niobium oxide, and
tantalum oxide.
[0108] The electricity storage layer refers to a layer composed of
an anchoring structure formed as the result of the particles of the
electrode material for batteries being necking-bonded to one
another and having an electricity storage effect.
[0109] If a dye to be fixated on a surface of the electricity
generation layer of a dye-sensitized solar cell is firmly fixed on
a surface of the electrode material for batteries composing the
anchoring structure in the electricity storage layer, it is
possible to form an electricity generation and storage layer. The
electricity generation and storage layer is a layer which generates
electricity when exposed to the irradiation of light, such as solar
light, and has an electricity storage effect.
[0110] In order to settle the surface potential of the electrode
material for batteries used in the electricity storage layer or the
electricity generation and storage layer or to improve the
necking-bondability of the particles of the material to one
another, it is effective to dispose a metal oxide coating film on
the electrode material for batteries or add second powder made from
metal oxide to the electrode material. Examples of the metal oxide
coating film include those made from metal oxides, such as yttrium
oxide and cerium oxide. Examples of the second powder include metal
oxide powder made from metal oxides, such as magnesium oxide,
cobalt oxide, manganese oxide, yttrium oxide, and ITO.
(Advantageous Effects of Electrode Material Paste for
Batteries)
[0111] According to the electrode material paste for batteries of
the present invention, it is possible to form an electricity
storage layer or an electricity generation and storage layer high
in electricity storage efficiency.
[0112] Hence, according to the electrode material paste for
batteries of the present invention, it is possible to efficiently
fabricate a storage battery or a dye-sensitized solar cell high in
electricity storage efficiency.
[Dye-Sensitized Solar Cell]
[0113] The dye-sensitized solar cell of the present invention uses
the electrode material for batteries of the present invention.
[0114] The dye-sensitized solar cell of the present invention is a
concept that encompasses a first dye-sensitized solar cell
including an electricity generation and storage layer formed using
an electrode material for batteries on a surface of which a dye of
the dye-sensitized solar cell is fixated, and a second
dye-sensitized solar cell including an electricity generation layer
and an electricity storage layer formed on a surface of this
electricity generation layer as the result of the particles of the
electrode material for batteries being necking-bonded to one
another.
(First Dye-Sensitized Solar Cell)
[0115] The first dye-sensitized solar cell will be described with
reference to the accompanying drawings. FIG. 1 is a cross-sectional
view of the first dye-sensitized solar cell of the present
invention.
[0116] As illustrated in FIG. 1, a first dye-sensitized solar cell
1A comprises: an electricity generation-side complex 91; a
non-electricity generation-side complex 92 disposed oppositely to
the electricity generation-side complex 91, and a spacer 56 for
externally dividing off a space 59 formed between the electricity
generation-side complex 91 and the non-electricity generation-side
complex 92, wherein an electricity generation and storage layer 81
is formed within the space 59.
[0117] The electricity generation-side complex 91 is such that a
transparent conductive film 52 is formed on a surface of a glass
substrate 51a. The non-electricity generation-side complex 92 is
such that a transparent conductive film 52 and a Pt counter
electrode 53 are formed in this order on a surface of a glass
substrate 51b. As the material of the transparent conductive films
52, for example, ITO, ATO or FTO is used.
[0118] The electricity generation-side complex 91 and the
non-electricity generation-side complex 92 are disposed so that the
transparent conductive film 52 of the electricity generation-side
complex 91 and the Pt counter electrode 53 of the non-electricity
generation-side complex 92 face to each other. The Pt counter
electrode 53 is formed by, for example, sputtering Pt onto a
surface of the transparent conductive film 52.
[0119] It is possible to use an electroconductive organic material
in place of the Pt counter electrode. Examples of the
electroconductive organic material include
polyethylenedioxythiophene (PEDOT). The electricity generation-side
complex 91 and the non-electricity generation-side complex 92 are
preferably arranged away from each other at a distance of, for
example, 30 to 300 .mu.m. If the electricity generation-side
complex 91 and the non-electricity generation-side complex 92 are
arranged away from each other at a distance longer than 300 .mu.M,
the separation distance between the electricity generation-side
complex 91 and the non-electricity generation-side complex 92 is
preferably no longer than 20 times the thickness of the electricity
generation and storage layer 81. If the electricity generation-side
complex 91 and the non-electricity generation-side complex 92 are
arranged away from each other at a distance longer than 20 times
the thickness of the electricity generation and storage layer 81,
the electricity generation and storage layer 81 and the Pt counter
electrode 53 are located too far away from each other. This
arrangement may therefore degrade power generation efficiency and
electricity storage efficiency.
[0120] The spacer 56 for externally dividing off the space 59
formed between the electricity generation-side complex 91 and the
non-electricity generation-side complex 92 are disposed between the
transparent conductive film 52 of the electricity generation-side
complex 91 and the Pt counter electrode 53 of the non-electricity
generation-side complex 92. The spacer 56 is composed of synthetic
resin, such as ionomer resin.
[0121] An electrolytic solution 70 is sealed in the space 59
divided off by the electricity generation-side complex 91, the
non-electricity generation-side complex 92 and the spacer 56.
[0122] The transparent conductive film 52 of the electricity
generation-side complex 91 and the Pt counter electrode 53 of the
non-electricity generation-side complex 92 are electrically
connected to each other with a lead wire 57 disposed on an outer
side surface of the spacer 56.
[0123] In the first dye-sensitized solar cell 1A, the electricity
generation and storage layer 81 is formed on a surface of the
transparent conductive film 52 of the electricity generation-side
complex 91 within the space 59 divided off by the electricity
generation-side complex 91, the non-electricity generation-side
complex 92 and the spacer 56.
<Electricity Generation and Storage Layer>
[0124] The electricity generation and storage layer 81 is a layer
in which a dye 30 of the dye-sensitized solar cell is fixated on a
surface of the electrode material 20 for batteries in an anchoring
structure formed as the result of the particles of the electrode
material 20 for batteries being necking-bonded to one another. The
electricity generation and storage layer 81 generates electricity
when exposed to the irradiation of light, such as solar light, and
has an electricity storage effect.
[0125] As the dye 30 of the dye-sensitized solar cell, a
ruthenium-based dye, for example, is used. As the ruthenium-based
dye, a dye prepared by drying a dye solution N719 made by
Sigma-Aldrich Co. LLC., for example, is used.
[0126] In the electricity generation and storage layer 81, voids
are formed among the particles of the electrode material 20 for
batteries on a surface of which the dye 30 is fixated. Voids are
normally 5 nm or larger in size. Here, the void size is determined
by taking a magnified photograph (100000.times. magnification or
higher) of the electricity generation and storage layer
corresponding to a 1 .mu.m.times.3 .mu.m cross section thereof. The
void size is thus defined as the longest diagonal line of a void
shown in this magnified photograph. In the magnified photograph,
the electrode material and the voids can be distinguished from each
other by a difference in contrast.
[0127] The electricity generation and storage layer 81 is normally
20 to 80% by volume in voidage (void ratio). Here, voidage is
determined by taking a magnified photograph (100000.times.
magnification or higher) of the electricity generation and storage
layer corresponding to a 1 .mu.m.times.3 .mu.m cross section
thereof and calculating the total area ratio (%) of voids in this
magnified photograph. Voidage is thus defined as this total area
ratio (%) of voids.
<Method for Manufacturing Electricity Generation and Storage
Layer>
[0128] A method for manufacturing the electricity generation and
storage layer 81 will be described hereunder.
[0129] First, a paste containing an electrode material for
batteries, such as the electrode material paste for batteries of
the present invention, is prepared.
[0130] In the paste containing the electrode material for
batteries, the blending ratio of the binder when the total amount
of the electrode material for batteries, the binder and the solvent
is 100% by mass is normally 3 to 30% by mass in general, as
described above, since the voidage of the electricity generation
and storage layer 81 is likely to be 20 to 80% by volume, thus
being preferable.
[0131] Next, the paste containing the electrode material for
batteries is coated on a surface of the transparent conductive film
52 of the electricity generation-side complex 91 using a screen
printing method or the like. Coating is preferably performed a
plural number of times until a required thickness is reached.
[0132] In addition, the electricity generation-side complex 91 on
which the paste containing the electrode material for batteries is
coated is calcinated (baked). Thus, an anchoring structure formed
as the result of the particles of the electrode material 20 for
batteries being necking-bonded to one another is formed on the
surface of the transparent conductive film 52 of the electricity
generation-side complex 91.
[0133] Calcination temperature is normally set to 500.degree. C. or
lower, and preferably 200 to 500.degree. C. Calcination temperature
is preferably 500.degree. C. or lower since no damage is caused to
the glass substrate 51a.
[0134] The rate of temperature rise at the time of calcination is
preferably 100.degree. C./h or higher since the binder in the paste
containing the electrode material for batteries can be thermally
decomposed all at once, and therefore, the size of voids among the
particles of the electrode material 20 for batteries can be easily
adjusted to 5 nm or larger.
[0135] Next, the electricity generation-side complex 91 in which
the anchoring structure formed as the result of the particles of
the electrode material 20 for batteries being necking-bonded to one
another is formed on the surface of the transparent conductive film
52 is immersed in a solution containing the dye 30 for the
dye-sensitized solar cell and then dried. Consequently, the dye 30
is fixated on a surface of the electrode material 20 for batteries,
thereby to form the electricity generation and storage layer
81.
[0136] In this connection, the electrode material 20 for batteries
of the anchoring structure is preferably surface-treated before the
anchoring structure formed as the result of the particles of the
electrode material 20 for batteries being necking-bonded to one
another is immersed in the solution containing the dye 30, since
the dye 30 is easily fixated on the surface of the electrode
material 20 for batteries. As such surface treatment, there is
used, for example, a method for forming a metal oxide film, such as
a Y.sub.2O.sub.3 film, on the surface of the electrode material 20
for batteries.
[0137] The electricity generation-side complex 91 in which the
electricity generation and storage layer 81 is formed is disposed
oppositely to the non-electricity generation-side complex 92
fabricated separately. Thereafter, the electricity generation-side
complex 91, the non-electricity generation-side complex 92 and the
spacer 56 having an unillustrated electrolytic solution inlet are
thermocompression-bonded and integrated with one another. In
addition, the electrolytic solution 70 is injected from the
electrolytic solution inlet of the spacer 56 into the space 59, the
electrolytic solution inlet is sealed up with resin, and the
transparent conductive film 52 and the Pt counter electrode 53 are
electrically connected with the lead wire 57. Consequently, there
is obtained the first dye-sensitized solar cell 1A.
[0138] The electrolytic solution 70 is preferably a mixture of an
electrolytic composition and an organic solvent. In addition, the
electrolytic composition is preferably a mixture of iodine and
iodide. As the iodide, lithium iodide (LiI), for example, is
used.
[0139] In a case where a mixture of iodine and iodide is used as
the electrolytic composition, the concentration of iodine in the
electrolytic solution is preferably set to 0.01 to 5.0 mol/L, and
the concentration of iodide in the electrolytic solution is
preferably set to 0.5 to 5.0 mol/L. Iodine and iodide
concentrations within these ranges enable reductions in the
migration resistance of charges in the electrolytic solution and in
reaction resistance at the counter electrode.
[0140] Mixing the organic solvent with the electrolytic solution
enables a reduction in the viscosity of the electrolytic
composition, thereby facilitating the infiltration (penetration) of
the electrolytic solution into the electricity generation and
storage layer 81. As the organic solvent, cyclic carbonate and
cyclic ester are preferably used. Cyclic carbonate and cyclic ester
are efficient in charge exchange, and therefore, use of cyclic
carbonate or cyclic ester makes available the effect of decreasing
internal resistance. As cyclic carbonate, ethylene carbonate,
propylene carbonate or butylene carbonate, for example, is used. As
cyclic ester, .gamma.-butyllactone, .delta.-valerolactone or
.delta.-caprolactone, for example, is used.
<Operation of First Dye-Sensitized Solar Cell>
[0141] The operation of the first dye-sensitized solar cell 1A will
be described hereunder with reference to the accompanying
drawings.
[0142] As illustrated in FIG. 1, light 75, when radiated to a glass
substrate 51a of the first dye-sensitized solar cell 1A, transmits
through the glass substrate 51a and the transparent conductive film
52, and is received by the dye 30 of the electricity generation and
storage layer 81.
[0143] The dye 30 is subjected to excitation suited to
photoelectric conversion properties by the received light, and
generates electrons. That is, the dye 30 generates electricity.
Electrons generated at the dye 30 flow into the electrode material
20 for batteries of the electricity generation and storage layer
81.
[0144] Some of the electrons flowing into the electrode material 20
for batteries of the electricity generation and storage layer 81
flow into the lead wire 57 through the transparent conductive film
52 and flow through the lead wire 57 in the direction shown by
reference numeral 61. The rest of the electrons flowing into the
electrode material 20 for batteries of the electricity generation
and storage layer 81 stays in the electrode material 20 for
batteries and is stored therein.
[0145] Hence, according to the first dye-sensitized solar cell 1A,
it is possible to supply electricity to external equipment even if
the amount of solar insolation decreases drastically. Furthermore,
it is possible to take measures, such as switchover to a general
commercial power source, while supplying electricity to the
external equipment by taking advantage of electricity storage
functions.
(Second Dye-Sensitized Solar Cell)
[0146] The second dye-sensitized solar cell will be described
hereunder with reference to the accompanying drawings. FIG. 2 is a
cross-sectional view of the second dye-sensitized solar cell of the
present invention.
[0147] A second dye-sensitized solar cell 1B illustrated in FIG. 2,
when compared with the first dye-sensitized solar cell 1A
illustrated in FIG. 1, differs therefrom in that an electricity
generation layer 82 and an electricity storage layer 83 are formed
in place of the electricity generation and storage layer 81 and
that a mesh-like electrode 55 having contact with a surface of the
electricity storage layer 83 is disposed. The rest of the second
dye-sensitized solar cell 1B is the same as the first
dye-sensitized solar cell 1A illustrated in FIG. 1.
[0148] Accordingly, constituent elements, among those of the second
dye-sensitized solar cell 1B illustrated in FIG. 2, which are the
same as constituent elements of the first dye-sensitized solar cell
1A illustrated in FIG. 1 are denoted by the same reference numerals
and characters and the description of the configuration and
operation of these constituent elements will be omitted or
simplified.
[0149] As illustrated in FIG. 2, the second dye-sensitized solar
cell 1B comprises an electricity generation-side complex 91, a
non-electricity generation-side complex 92 disposed oppositely to
the electricity generation-side complex 91, and a spacer 56 for
externally dividing off a space 59 formed between the electricity
generation-side complex 91 and the non-electricity generation-side
complex 92, wherein an electricity generation layer 82 and an
electricity storage layer 83 are formed within the space 59.
[0150] A mesh-like electrode 55 is disposed on a surface of the
electricity storage layer 83 within the space 59 divided off by the
electricity generation-side complex 91, the non-electricity
generation-side complex 92 and the spacer 56, so as to have contact
with the electricity storage layer 83. The mesh-like electrode 55
is a reticular electrode formed from, for example, Ti, and allows
an electrolytic solution 70 to flow in the thickness direction
thereof.
[0151] A transparent conductive film 52 of the electricity
generation-side complex 91 and a Pt counter electrode 53 of the
non-electricity generation-side complex 92 are electrically
connected to each other with a lead wire 57 disposed on the outer
side surface of the spacer 56. This lead wire 57 is branched to
also connect to the mesh-like electrode 55.
[0152] Consequently, the lead wire 57 is electrically connected to
the transparent conductive film 52 of the electricity
generation-side complex 91, the Pt counter electrode 53 of the
non-electricity generation-side complex 92 and the mesh-like
electrode 55.
[0153] In the second dye-sensitized solar cell 1B, the electricity
generation layer 82 and the electricity storage layer 83 are formed
in this order on a surface of the transparent conductive film 52 of
the electricity generation-side complex 91 within the space 59
divided off by the electricity generation-side complex 91, the
non-electricity generation-side complex 92 and the spacer 56.
<Electricity Generation Layer>
[0154] The electricity generation layer 82 is a layer composed of
an anchoring structure formed as the result of the particles of
titanium oxide (TiO.sub.2) 10 serving as a photoelectric conversion
material being firmly bonded to one another due to necking or the
like. The electricity generation layer 82, when exposed to the
irradiation of light, such as solar light, generates
electricity.
[0155] Here, the photoelectric conversion material refers to a
material having photoelectric conversion properties. Preferably,
the photoelectric conversion material is powder.
[0156] As the photoelectric conversion material, it is possible to
use at least one type of material selected from the group
consisting of, for example, titanium oxide, tin oxide, tungsten
oxide, zinc oxide, zirconium oxide, neodymium oxide, hafnium oxide,
strontium oxide, indium oxide, cerium oxide, yttrium oxide,
lanthanum oxide, vanadium oxide, niobium oxide, and tantalum oxide,
in addition to the titanium oxide (TiO.sub.2) as an elementary
substance illustrated in FIG. 2.
<Method for Manufacturing Electricity Generation Layer>
[0157] A method for manufacturing the electricity generation layer
82 will be described hereunder.
[0158] First, titanium oxide paste containing titanium oxide
(TiO.sub.2) 10 serving as a photoelectric conversion material is
prepared.
[0159] The titanium oxide paste contains, for example, the titanium
oxide (TiO.sub.2) 10, a binder, and a solvent. As the binder and
the solvent for use in the titanium oxide paste, it is possible to
use, for example, the same binder and solvent as used to prepare
the electrode material paste for batteries of the present
invention.
[0160] In the titanium oxide paste, the blending ratio of the
binder when the total amount of the titanium oxide TiO.sub.2 10,
the binder and the solvent is assumed to be 100% by mass is
preferably 3 to 30% by mass in general, as described above, since
the voidage (void ratio) of the electricity generation layer 82 is
likely to be 20 to 80% by volume.
[0161] If a substance other than titanium oxide (TiO.sub.2) is used
as the photoelectric conversion material 10 of the electricity
generation layer 82, paste containing this substance is
prepared.
[0162] Next, the titanium oxide paste is coated on a surface of the
transparent conductive film 52 of the electricity generation-side
complex 91 using a screen printing method or the like. Coating is
preferably performed a plural number of times until a required
thickness is reached.
[0163] In addition, the electricity generation-side complex 91 on
which the titanium oxide paste is coated is calcinated (baked).
Thus, an anchoring structure formed as the result of the particles
of the titanium oxide (TiO.sub.2) 10 being necking-bonded to one
another is formed on the surface of the transparent conductive film
52 of the electricity generation-side complex 91.
[0164] Calcination conditions are the same as those described in
the method for manufacturing the electricity generation and storage
layer 81 of the first dye-sensitized solar cell 1A illustrated in
FIG. 1, and therefore, will not be discussed here.
<Electricity Storage Layer>
[0165] The electricity storage layer 83 is formed on a surface of
the electricity generation layer 82.
[0166] The electricity storage layer 83 is a layer composed of an
anchoring structure formed as the result of the particles of the
electrode material 20 for batteries being necking-bonded to one
another. The electricity storage layer 83 has an electricity
storage effect.
[0167] The electricity storage layer 83 is normally 20 to 80% by
volume in voidage. The definition of voidage is the same as that of
the voidage of the electricity generation and storage layer 81.
<Method for Manufacturing Electricity Storage Layer>
[0168] A method for manufacturing the electricity storage layer 83,
when compared with the method for manufacturing the electricity
generation and storage layer 81 of the first dye-sensitized solar
cell 1A illustrated in FIG. 1, is the same as the method except
that the electricity generation-side complex 91 in which the
anchoring structure is formed as the result of the particles of the
electrode material 20 for batteries being necking-bonded to one
another is neither immersed in the solution containing the dye 30
of the dye-sensitized solar cell nor dried thereafter. Accordingly,
the method for manufacturing the electricity storage layer 83 will
not be discussed here.
[0169] In the electricity generation-side complex 91 in which the
electricity generation layer 82 and the electricity storage layer
83 are formed, the mesh-like electrode 55 is disposed so as to have
contact with a surface of the electricity storage layer 83.
[0170] The electricity generation-side complex 91 in which the
mesh-like electrode 55 is disposed is arranged oppositely to the
non-electricity generation-side complex 92 fabricated separately.
Thereafter, the electricity generation-side complex 91, the
non-electricity generation-side complex 92 and the spacer 56 having
an unillustrated electrolytic solution inlet are
thermocompression-bonded and integrated with one another. In
addition, the electrolytic solution 70 is injected from the
electrolytic solution inlet of the spacer 56 into the space 59, the
electrolytic solution inlet is sealed up with resin, and the
transparent conductive film 52, the Pt counter electrode 53 and the
mesh-like electrode 55 are electrically connected with the lead
wire 57. Consequently, there is obtained the second dye-sensitized
solar cell 1B.
<Operation of Second Dye-Sensitized Solar Cell>
[0171] The operation of the second dye-sensitized solar cell 1B
will be described hereunder with reference to the accompanying
drawings.
[0172] As illustrated in FIG. 2, light 75, when radiated to a glass
substrate 51a of the second dye-sensitized solar cell 1B, transmits
through the glass substrate 51a and the transparent conductive film
52, and is received by the dye 30 of the electricity generation
layer 82.
[0173] The dye 30 is subjected to excitation suited to
photoelectric conversion properties by the received light, and
generates electrons. That is, the dye 30 generates electricity.
Electrons generated at the dye 30 flow into the titanium oxide
(TiO.sub.2) 10 which is the photoelectric conversion material of
the electricity generation layer 82.
[0174] Some of the electrons flowing into the titanium oxide
(TiO.sub.2) 10 of the electricity generation layer 82 flow into the
lead wire 57 through the transparent conductive film 52 and flow
through the lead wire 57 in the direction shown by reference
numeral 61. The rest of the electrons flowing into the titanium
oxide (TiO.sub.2) 10 of the electricity generation layer 82 flows
into the electricity storage layer 83 and is stored in the
electrode material 20 for batteries of the electricity storage
layer 83.
[0175] Hence, according to the second dye-sensitized solar cell 1B,
it is possible to supply electricity to external equipment even if
the amount of solar insolation decreases drastically. Furthermore,
it is possible to take measures, such as switchover to a general
commercial power source, while supplying electricity to the
external equipment by taking advantage of electricity storage
functions.
(Advantageous Effects of Dye-Sensitized Solar Cell)
[0176] The dye-sensitized solar cell of the present invention is
high in electricity storage efficiency since the electrode material
for batteries contained in the electricity generation and storage
layer or the electricity storage layer is high in electricity
storage efficiency.
[Storage Battery]
[0177] A storage battery of the present invention uses the
electrode material for batteries of the present invention.
[0178] The storage battery of the present invention will be
described hereunder with reference to the accompanying drawings.
FIG. 3 is a cross-sectional view of the storage battery of the
present invention.
[0179] As illustrated in FIG. 3, a storage battery 2 of the present
invention comprises an electrode 54, a non-electricity
generation-side complex 92 disposed oppositely to the electrode 54,
and a spacer 56 for externally dividing off a space 59 formed
between the electrode 54 and the non-electricity generation-side
complex 92, wherein an electricity storage layer 83 is formed
within the space 59.
[0180] As the result of being combined with a solar cell 5 to which
the storage battery 2 is electrically connected with a lead wire
57, the storage battery 2 forms a solar cell-storage battery
composite device 7 having both an electricity generation effect and
an electricity storage effect.
[0181] The storage battery 2 illustrated in FIG. 3, when compared
with the second dye-sensitized solar cell 1B illustrated in FIG. 2,
differs in that the electrode 54 is used in place of the
electricity generation-side complex 91, that the electricity
generation layer 82 is not formed, and that the mesh-like electrode
55 is not disposed. The rest of the storage battery 2 is the same
as the second dye-sensitized solar cell 1B illustrated in FIG.
2.
[0182] Accordingly, constituent elements, among those of the
storage battery 2 illustrated in FIG. 3, which are the same as
constituent elements of the second dye-sensitized solar cell 1B
illustrated in FIG. 2 are denoted by the same reference numerals
and characters and the description of the configuration and
operation of these constituent elements will be omitted or
simplified.
[0183] The electrode 54 is not limited in particular in material,
structure and the like. The electrode 54 may be made from metal or
carbon, or may be such that the transparent conductive film 52 is
formed on a surface of the glass substrate 51a, as in the case of
the electricity generation-side complex 91. A metal substrate may
be used in place of the glass substrate 51b on which the
transparent conductive film 52 is disposed. As the metal substrate,
a titanium plate or a ruthenium plate is preferably used since it
is resistant to corrosion by an electrolytic solution. In addition,
use of the metal substrate eliminates the need to separately
dispose a transparent conductive film. In this case, insulation is
performed on a surface of the metal substrate on the side thereof
not in contact with an electrolytic solution.
[0184] The solar cell 5 is not limited in particular in material,
structure and the like. Examples of the material of the solar cell
5 include Si, CIGS (Cu(In, Ga)Se.sub.2), TiO.sub.2, and DSSC
(dye-sensitized solar cell).
<Electricity Storage Layer>
[0185] The electricity storage layer 83 is the same in
configuration as the electricity storage layer 83 of the second
dye-sensitized solar cell 1B illustrated in FIG. 2. A method for
manufacturing the electricity storage layer 83 is also the same as
the method for manufacturing the electricity storage layer 83 of
the second dye-sensitized solar cell 1B illustrated in FIG. 2.
[0186] Accordingly, the description of the configuration and
operation of the electricity storage layer 83 will be omitted or
simplified.
<Operation of Storage Battery>
[0187] The operation of the storage battery 2 will be described
with reference to the accompanying drawings.
[0188] As illustrated in FIG. 3, some of electrons generated at the
solar cell 5 flow through the lead wire 57 toward the Pt counter
electrode 53, as shown by reference numeral 61. The rest of the
electrons generated at the solar cell 5 flows from the lead wire 57
to the electrode 54.
[0189] The electrons flowing into the electrode 54 flow from the
electrode 54 to the electricity storage layer 83 and are stored in
the electrode material 20 for batteries constituting the
electricity storage layer 83.
[0190] Hence, according to the storage battery 2, it is possible to
supply electricity to external equipment even if the amount of
solar insolation decreases drastically. Furthermore, it is possible
to take measures, such as switchover to a general commercial power
source, while supplying electricity to the external equipment by
taking advantage of electricity storage functions.
(Advantageous Effects of Storage Battery)
[0191] The storage battery of the present invention is high in
electricity storage efficiency since the electrode material for
batteries contained in the electricity storage layer is high in
electricity storage efficiency.
EXAMPLES
[0192] Examples of the present invention will be described
hereinafter. However, the present invention should not be construed
as being limited to these examples.
Practical Example 1
Manufacture of WO.sub.3 Powder
<Plasma Treatment Step>
[0193] Tungsten trioxide (WO.sub.3) powder having an average
particle diameter of 3 .mu.m was prepared as raw material powder.
This raw material powder was sprayed into RF plasma using the
atmosphere (air) as a carrier gas, so as to be 1 m/s in average
flow velocity. Thus, a plasma treatment step was carried out in
which an oxidation reaction was induced while sublimating the raw
material powder. The temperature of plasma flame at the time of
plasma treatment was set to 10000.degree. C.
<Rapid Cooling Step>
[0194] After the plasma treatment, a rapid cooling step was carried
out on WO.sub.3 powder having flown out of plasma flame under the
conditions shown in Table 1. That is, the rapid cooling step was
carried out after setting a rapid cooling distance in a rapid
cooling area to 2 m and a cooling rate in the rapid cooling area to
1000.degree. C./s. Consequently, there was obtained the WO.sub.3
powder.
TABLE-US-00001 TABLE 1 Plasma BET Specific Treatment Rapid Cooling
Step Surface Area Composition Process Rapid of Electrode of
Electrode Plasma Flame Cooling Rate Cooling Heat Treatment Step
Material Material Temperature of WO.sub.3 Distance Temperature Time
for Battery Sample No. for Battery (.degree. C.) (.degree. C./s)
(m) (.degree. C.) (H) (m.sup.2/g) Example 1 WO.sub.3 10000 1000 2
-- -- 120 Example 2 WO.sub.3 10000 1000 1.5 300 1 100 Example 3
WO.sub.3 10000 1000 2 450 50 50 Example 4 WO.sub.3 10000 1000 2 600
1 36 Example 5 WO.sub.3 10000 1000 2 700 1 18
(Evaluation of WO.sub.3 Powder)
[0195] The BET specific surface area of the WO.sub.3 powder thus
obtained was measured, and a Raman spectroscopic analysis was
performed to detect peaks.
<Measuring Conditions in Raman Spectroscopic Analysis>
[0196] Measurements were made using a spectrograph PDP-320 made by
Photon Design Corporation.
[0197] For measuring conditions, the measurement mode of the
spectrograph was specified as "Microscopic Raman", the measurement
magnification thereof as 100.times., a beam diameter as 1 .mu.m or
smaller, a light source as an Ar.sup.+ laser having a wavelength of
514.5 nm, laser power at the laser tube of the Ar.sup.+ laser as
0.5 mW, a diffraction grating as Single 600 gr/mm, a cross slit as
100 .mu.m, and a slit as 100 .mu.m. A 1340-channel CCD made by
Nippon Roper, K. K. was used as a detector.
[0198] The measuring range of the detector was set to 100 to 1500
cm.sup.-1.
[0199] Table 1 shows the manufacturing conditions of the WO.sub.3
powder and the results of measuring the BET specific surface
area.
[0200] Table 2 shows the measurement results of Raman spectroscopic
analysis.
[0201] FIG. 4 shows the measurement results of Raman spectroscopic
analysis.
TABLE-US-00002 TABLE 2 First Peak Second Peak Third Peak Fourth
Peak Fifth Peak Peak Peak Peak Peak Peak Peak Peak Peak Peak Peak
Position Intensity I.sub.1 Position Intensity I.sub.2 Position
Intensity I.sub.3 Position Intensity I.sub.4 Position Intensity
I.sub.5 sample No. (cm.sup.-1) (cps) (cm.sup.-1) (cps) (cm.sup.-1)
(cps) (cm.sup.-1) (cps) (cm.sup.-1) (cps) Example 1 269 359 695 688
801 1890 132 132 935 128 Example 2 270 1060 703 1596 803 4812 130
341 938 229 Example 3 272 2023 712 2171 805 6242 136 788 935 76
Example 4 273 4517 717 6335 807 12771 135 2392 935 14 Example 5 274
25253 718 15778 808 56052 135 11534 None --
(Preparation of Electrode Material Paste for Batteries)
[0202] First, 59 parts by mass of terpineol serving as a solvent
and 4 parts by mass of ethyl cellulose serving as a binder were
agitated and mixed. Next, 28 parts by mass of the WO.sub.3 powder
was added while agitating the solvent in which the binder was
dissolved, and the solvent was continued to be agitated.
Consequently, there was obtained electrode material paste for
batteries.
[0203] The viscosity at 25.degree. C. of the electrode material
paste for batteries thus obtained was measured.
[0204] Table 3 shows the blending ratio of the WO.sub.3 powder, the
solvent and the binder in the electrode material paste for
batteries and the viscosity at 25.degree. C. of the electrode
material paste for batteries.
TABLE-US-00003 TABLE 3 Blending of Paste Solvent WO.sub.3 Powder
Binder Blending Viscosity Blending Ratio Blending Ratio Ratio of
Paste Sample No. (mass parts) Material (mass parts) (mass parts)
(cps) Example 1 28 Ethyl Cellurose 4 59 6300 Example 2 32 Ethyl
Cellurose 5 59 5400 Example 3 36 Ethyl Cellurose 5 59 4800 Example
4 36 Ethyl Cellurose 5 58 4100 Example 5 42 Ethyl Cellurose 7 57
1800
(Fabrication of First Dye-Sensitized Solar Cell)
[0205] The first dye-sensitized solar cell 1A illustrated in FIG. 1
was fabricated.
[0206] First, using an electricity generation-side complex 91 in
which a transparent conductive film 52 was formed on one side of a
glass substrate 51a having a thickness of 1.1 mm and a sheet
resistance of 5.OMEGA./.quadrature., the electrode material paste
for batteries was printed and coated on a surface of the
transparent conductive film 52 by a screen printing method. The
temperature of the glass substrate 51a coated with this paste was
raised from 25.degree. C. to 450.degree. C. in the atmosphere at a
temperature rise rate of 10.degree. C./min using an electric
furnace, and then the glass substrate 51a was calcinated at
450.degree. C. for 30 minutes. After calcination, there was formed
an electrode layer composed of a porous body formed on the surface
of the transparent conductive film 52 as the result of WO.sub.3
particles 20 being necking-bonded to one another. The porous body
was 65% in voidage and 15 .mu.m in thickness.
[0207] Next, the electrode layer thus fabricated was immersed in 40
mMol/L of an yttrium nitrate solution at 70.degree. C. for one
hour, cleaned with ethanol, and then dried. Thereafter, the
temperature of the electrode layer was raised from 25.degree. C. to
450.degree. C. at a temperature rise rate of 10.degree. C./min, and
then the electrode layer was calcinated at 450.degree. C. for 30
minutes. After calcination, the surfaces of the WO.sub.3 particles
20 were coated with a Y.sub.2O.sub.3 film. This Y.sub.2O.sub.3 film
was formed in order to facilitate the fixation of a dye 30 onto the
surfaces of the WO.sub.3 particles 20.
[0208] In addition, the electrode layer formed on the surface of
the transparent conductive film 52 was immersed in a dye solution
at room temperature for 48 hours to fabricate an electricity
generation and storage layer 81. As the dye solution, there was
used a solution prepared by dissolving N719
(di-tetrabutylammonium-cis-bis(isothiocyanate)bis(2,2'-bipyridyl-4,4'-dic-
arboxylate) ruthenium (II)) made by Sigma-Aldrich Co. LLC. in a
mixed solvent of one part by volume of acetonitrile and one part by
volume of t-butyl alcohol, so as to be 0.3 mMol/L in molarity. In
the electricity generation and storage layer 81, the dye 30 was
fixated on the surfaces of the WO.sub.3 particles 20 through the
Y.sub.2O.sub.3 film.
[0209] Furthermore, there was fabricated a non-electricity
generation-side complex 92 in which a transparent conductive film
52 and a Pt counter electrode 53 were formed in this order on a
surface of another glass substrate 51b. The Pt counter electrode 53
was prepared such that a platinum layer having a thickness of 80 nm
was formed on a surface of the transparent conductive film 52 by
sputtering.
[0210] Next, a tubular spacer resin 56 the thickness of which in a
thickness direction of the electricity generation and storage layer
81 was 60 .mu.m and in which electrolytic composition inlets were
arranged in four places was disposed so as to surround the
periphery of the electricity generation and storage layer 81.
Thereafter, the electricity generation-side complex 91 and the
non-electricity generation-side complex 92 heated to 110.degree. C.
were bonded to each other.
[0211] An electrolytic composition (electrolytic solution) 70 was
injected from an electrolytic composition inlet by means of a
syringe, and the inlet was sealed up with two-pack curable resin.
As the electrolytic solution, a solution was used in which 0.5
mol/L of lithium iodide, 0.05 mol/L of iodine, 0.58 mol/L of
t-butylpyridine, and 0.6 mol/L of
EtMeIm(CN).sub.2(1-ethyl-3-methylimidazolium dicyanamide) were
dissolved in an acetonitrile solvent as the constituents of the
electrolytic solution.
[0212] Consequently, there was obtained the first dye-sensitized
solar cell 1A.
(Evaluation of First Dye-Sensitized Solar Cell)
[0213] Using a solar simulator, light having a spectrum of AM1.5
and an intensity of 1 kW/m.sup.2 was radiated to the first
dye-sensitized solar cell 1A thus obtained to measure photoelectric
conversion efficiency. This photoelectric conversion efficiency was
defined as power generation efficiency.
[0214] Next, the first dye-sensitized solar cell 1A was connected
to a 510.OMEGA. resistor to measure current changes when light was
irradiated and when light was cut off. As a light source, there was
used a light source having a spectrum of AM 1.5 and an intensity of
1 kW/m.sup.2 available from the solar simulator.
[0215] In addition, tests were conducted to confirm the electricity
storage effect of the first dye-sensitized solar cell 1A. That is,
the first dye-sensitized solar cell 1A was left at rest for 20
seconds in a dark place to confirm that the amount of electrical
generation was zero. Thereafter, light was radiated to the solar
cell for 20 seconds, and was then cut off. Then, an evaluation was
made of discharge capacity as represented by the duration from when
the current value of the first dye-sensitized solar cell 1A was
maximum at the time of light irradiation to when the current value
decreased to 0 mA/cm.sup.2 after light interruption. This discharge
capacity was defined as electricity storage capacity.
[0216] Table 4 shows the power generation efficiency and
electricity storage capacity of the first dye-sensitized solar cell
1A.
TABLE-US-00004 TABLE 4 First Dye-Sensitized Second Dye-Sensitized
Storage Solar Cell Solar Cell Battery Electrode Power Electricity
Power Electricity Electricity Material Paste Generation Storage
Generation Storage Storage for Battery Efficiency Capacity
Efficiency Capacity Capacity Sample No. Type (%) (C/m.sup.2) (%)
(C/m.sup.2) (C/m.sup.2) Example 1 Example 1 1.1 156 -- -- --
Example 2 Example 2 1.2 160 -- -- -- Example 3 Example 3 2.0 245 --
-- -- Example 4 Example 4 1.6 200 -- -- -- Example 5 Example 5 1.4
160 -- -- -- Comparative Comparative 5.0 0 -- -- -- Example 1
Example 1 Example 6 Example 1 -- -- 3.2 148 -- Example 7 Example 2
-- -- 3.3 170 -- Example 8 Example 3 -- -- 4.1 260 -- Example 9
Example 4 -- -- 3.8 204 -- Example 10 Example 5 -- -- 3.2 156 --
Example 11 Example 1 -- -- -- -- 1000 Example 12 Example 2 -- -- --
-- 1100 Example 13 Example 3 -- -- -- -- 1200 Example 14 Example 4
-- -- -- -- 1200 Example 15 Example 5 -- -- -- -- 1100 Comparative
Comparative -- -- -- -- 0 Example 2 Example 1
Practical Examples 2 to 5
Manufacture of WO.sub.3 Powder
[0217] A plasma treatment step and a rapid cooling step were
carried out in the same way as in Practical Example 1, except that
the conditions of the rapid cooling step were changed as shown in
Table 1.
<Heat Treatment Step>
[0218] In the atmosphere, a heat treatment based on the conditions
shown in Table 1 was performed on WO.sub.3 powder obtained after
the rapid cooling step. When a heat treatment step was carried out,
there was obtained WO.sub.3 powder.
(Evaluation of WO.sub.3 Powder)
[0219] The BET specific surface area of the WO.sub.3 powder thus
obtained was measured in the same way as in Practical Example 1,
and a Raman spectroscopic analysis was performed to detect
peaks.
[0220] FIG. 4 illustrates the measurement results of Raman
spectroscopic analyses in Practical Examples 3 and 4.
(Preparation of Electrode Material Paste for Batteries)
[0221] Electrode material paste for batteries was prepared in the
same way as in Practical Example 1, except that the conditions for
preparing the electrode material paste for batteries were changed
as shown in Table 3.
[0222] The viscosity at 25.degree. C. of the electrode material
paste for batteries thus obtained was measured in the same way as
in Practical Example 1.
(Fabrication of First Dye-Sensitized Solar Cell)
[0223] First dye-sensitized solar cells 1A were fabricated and
evaluated in the same way as in Practical Example 1, except that
electrode material paste for batteries having the composition shown
in Table 3 was used in place of the electrode material paste for
batteries of Practical Example 1.
[0224] Table 4 shows the power generation efficiency and
electricity storage capacity of the first dye-sensitized solar
cells 1A.
Comparative Example 1
[0225] A dye-sensitized solar cell was fabricated in the same way
as in Practical Example 1, except that titanium oxide paste
containing titanium oxide (TiO.sub.2) having an average particle
diameter of 13 .mu.m was used in place of the electrode material
paste for batteries of Practical Example 1.
[0226] The dye-sensitized solar cell thus obtained was configured
such that the WO.sub.3 particles 20 constituting the electricity
generation and storage layer 81 were replaced with TiO.sub.2
particles in the first dye-sensitized solar cell 1A illustrated in
FIG. 1.
[0227] Thus obtained dye-sensitized solar cell was evaluated in the
same way as in Practical Example 1.
[0228] Table 4 shows the power generation efficiency and
electricity storage capacity of the dye-sensitized solar cell.
Practical Example 6
Fabrication of Second Dye-Sensitized Solar Cell
[0229] The second dye-sensitized solar cell 1B illustrated in FIG.
2 was fabricated.
[0230] First, using an electricity generation-side complex 91 in
which a transparent conductive film 52 was formed on one side of a
glass substrate 51a having a thickness of 1.1 mm and a sheet
resistance of 5.OMEGA./.quadrature., titanium oxide paste
containing titanium oxide (TiO.sub.2) 10 having an average particle
diameter of 13 .mu.m was printed and coated on a surface of the
transparent conductive film 52 by a screen printing method. The
glass substrate 51a coated with this paste was calcinated in the
atmosphere at 450.degree. C. for 30 minutes using an electric
furnace. After calcination, there was formed an electrode layer
composed of a porous body formed on the surface of the transparent
conductive film 52 as the result of the particles of the TiO.sub.2
10 being necking-bonded to one another. The porous body was 50% in
voidage and 10 .mu.m in thickness.
[0231] Next, the electrode material paste for batteries of
Practical Example 1 was printed and coated by a screen printing
method on a surface of the electrode layer composed of a porous
body formed as the result of the particles of the TiO.sub.2 10
being necking-bonded to one another. The temperature of the glass
substrate 51a coated with this paste was raised from 25.degree. C.
to 450.degree. C. in the atmosphere at a temperature rise rate of
10.degree. C./min using an electric furnace, and then the glass
substrate 51a was calcinated at 450.degree. C. for 30 minutes.
After completion of calcination, there was formed an electrode
layer composed of a porous body formed on the surface of the
transparent conductive film 52 as the result of WO.sub.3 particles
20 being necking-bonded to one another. The porous body was 65% in
voidage and 10 .mu.m in thickness.
[0232] In addition, as an extraction electrode for external
connection, a Ti mesh electrode 55 was formed on a surface of the
electrode layer composed of the porous body formed as the result of
the WO.sub.3 particles 20 being necking-bonded to one another. In
order to prevent the transparent conductive film 52 and the Ti mesh
electrode 55 from coming into contact with each other, the lead-out
portion of the extraction electrode was insulation-treated.
[0233] Next, the two-layered electrode layer thus fabricated was
immersed in a dye solution at room temperature for 24 hours to
fabricate an electricity generation layer 82 and an electricity
storage layer 83. As the dye solution, there was used a solution
prepared by dissolving N719
(di-tetrabutylammonium-cis-bis(isothiocyanate)bis(2,2'-bipyridyl-4,4'-dic-
arboxylate) ruthenium (II)) made by Sigma-Aldrich Co. LLC. in a
mixed solvent of one part by volume of acetonitrile and one part by
volume of t-butyl alcohol, so as to be 0.3 mMol/L in molarity. In
the electricity generation and storage layer 81, the dye 30 was
fixated on the surfaces of the WO.sub.3 particles 20 through the
Y.sub.2O.sub.3 film.
[0234] Furthermore, there was fabricated a non-electricity
generation-side complex 92 in which a transparent conductive film
52 and a Pt counter electrode 53 were formed in this order on a
surface of another glass substrate 51b. The Pt counter electrode 53
was prepared such that a platinum layer having a thickness of 80 nm
was formed on a surface of the transparent conductive film 52 by
sputtering.
[0235] Next, a tubular spacer resin 56 the thickness of which in a
thickness direction of the electricity generation and storage layer
81 was 60 .mu.m and in which electrolytic composition inlets were
arranged in four places was disposed so as to surround the
periphery of the electricity generation and storage layer 81.
Thereafter, the electricity generation side complex 91 and the
non-electricity generation-side complex 92 heated to 110.degree. C.
were bonded to each other.
[0236] An electrolytic composition (electrolytic solution) 70 was
injected from an electrolytic composition inlet with a syringe, and
the inlet was sealed up with UV-curable resin. As the electrolytic
solution, there was used a solution in which 0.5 mol/L of lithium
iodide, 0.05 mol/L of iodine, 0.58 mol/L of t-butylpyridine, and
0.6 mol/L of EtMeIm(CN).sub.2(1-ethyl-3-methylimidazolium
dicyanamide) were dissolved in an acetonitrile solvent as the
constituents of the electrolytic solution.
[0237] Consequently, there was obtained the second dye-sensitized
solar cell 1B.
(Evaluation of Second Dye-Sensitized Solar Cell)
[0238] The second dye-sensitized solar cell 1B was evaluated in the
same way as the first dye-sensitized solar cell 1A of Practical
Example 1.
[0239] Table 4 shows the power generation efficiency and
electricity storage capacity of the second dye-sensitized solar
cell 1B.
Practical Examples 7 to 10
[0240] Second dye-sensitized solar cells 1B were fabricated and
evaluated in the same way as in Practical Example 6, except that
the electrode material paste for batteries of Practical Examples 2
to 5 was used in place of the electrode material paste for
batteries of Practical Example 1.
[0241] Table 4 shows the power generation efficiency and
electricity storage capacity of the second dye-sensitized solar
cells 1B.
Practical Example 11
Fabrication of Storage Battery
[0242] The storage battery 2 illustrated in FIG. 3 was
fabricated.
[0243] First, using an electricity generation-side complex 91 in
which a transparent conductive film 52 was formed on one side of a
glass substrate 51a having a thickness of 1.1 mm and a sheet
resistance of 5.OMEGA./.quadrature., the electrode material paste
for batteries of Practical Example 1 was printed and coated on a
surface of the transparent conductive film 52 by a screen printing
method. The temperature of the glass substrate 51a coated with this
paste was raised from 25.degree. C. to 450.degree. C. in the
atmosphere at a temperature rise rate of 10.degree. C./min using an
electric furnace, and then the glass substrate 51a was calcinated
at 450.degree. C. for 30 minutes. After calcination, there was
formed an electricity storage layer 83 composed of a porous body
formed on the surface of the transparent conductive film 52 as the
result of WO.sub.3 particles 20 being necking-bonded to one
another. The porous body was 65% in voidage and 15 .mu.m in
thickness.
[0244] Next, a tubular spacer resin 56 the thickness of which in a
thickness direction of the electricity storage layer 83 was 15 and
in which electrolytic composition inlets were arranged in four
places was disposed so as to surround the periphery of the
electricity storage layer 83. Thereafter, the electrode 54 and the
non-electricity generation-side complex 92 heated to 110.degree. C.
were bonded to each other. The thickness of the spacer resin 56 was
set to 60
[0245] An electrolytic composition (electrolytic solution) 70 was
injected from an electrolytic composition inlet with a syringe, and
the inlet was sealed up with UV-curable resin. As the electrolytic
solution, there was used a solution in which 0.5 mol/L of lithium
iodide, 0.05 mol/L of iodine, 0.58 mol/L of t-butylpyridine, and
0.6 mol/L of EtMeIm(CN).sub.2(1-ethyl-3-methylimidazolium
dicyanamide) were dissolved in an acetonitrile solvent as the
constituents of the electrolytic solution.
[0246] Consequently, there was obtained the storage battery 2.
(Evaluation of Storage Battery)
[0247] The electricity storage performance of the storage battery 2
thus obtained was measured. The storage battery 2 was charged at
0.74 V for 640 seconds using an external power source. Thereafter,
electricity storage capacity was calculated from the value of a
current flowing through a 510.OMEGA. resistor connected to the
storage battery 2.
[0248] Table 4 shows the electricity storage capacity of the
storage battery 2.
Practical Examples 12 to 15
[0249] Storage batteries 2 were fabricated and evaluated in the
same way as in Practical Example 11, except that the electrode
material paste for batteries of Practical Examples 2 to 5 was used
in place of the electrode material paste for batteries of Practical
Example 1.
[0250] Table 4 shows the electricity storage capacity of the
storage batteries 2.
Comparative Example 2
[0251] A storage battery was fabricated in the same way as in
Practical Example 11, except that the titanium oxide paste of
Comparative Example 1 was used in place of the electrode material
paste for batteries of Practical Example 1.
[0252] The storage battery thus obtained was configured such that
the WO.sub.3 particles 20 constituting the electricity storage
layer 83 were replaced with TiO.sub.2 particles in the storage
battery 2 illustrated in FIG. 3.
[0253] The obtained storage battery was evaluated in the same way
as in Practical Example 11.
[0254] Table 4 shows the electricity storage capacity of the
storage battery.
[0255] As is clear from the results obtained from the
above-described practical and comparative examples, the
dye-sensitized solar cells and the storage batteries which use the
electrode material for batteries of the present invention have
proved to be high in electricity storage efficiency.
Practical Examples 16 to 18
Manufacture of WO.sub.3 Powder
[0256] Tungsten trioxide (WO.sub.3) powder having an average
particle diameter of 1 .mu.m was prepared as raw material powder.
This raw material powder was sprayed into RF plasma using the
atmosphere (air) as a carrier gas, so as to be 1 m/s in average
flow velocity. Thus, a plasma treatment step was carried out in
which an oxidation reaction was induced while sublimating the raw
material powder. The temperature of plasma flame at the time of
plasma treatment was set to 11000.degree. C.
<Rapid Cooling Step>
[0257] After completion of the plasma treatment, a rapid cooling
step was carried out on WO.sub.3 powder having flown out of plasma
flame under the conditions shown in Table 5. That is, the rapid
cooling step was carried out after setting a rapid cooling distance
in a rapid cooling area to no shorter than 1 m and a cooling rate
in the rapid cooling area to no lower than 1200.degree. C./s.
Consequently, there was obtained the WO.sub.3 powder.
TABLE-US-00005 TABLE 5 Electrode Material Plasma (WO.sub.3)
Treatment Rapid Cooling Process BET Process Rapid Heat Treating
Specific Average Composition Plasma Flame Cooling Rate Cooling
Process Surface Particle of Electrode Temperature of WO.sub.3
Distance Temperature Time Area Diameter Sample No. Material
(.degree. C.) (.degree. C./s) (m) (.degree. C.) (H) (m.sup.2/g)
(nm) Examples 16-18 WO.sub.3 11000 1200 or more 1 or more 700 1 19
45
<Heat Treatment Step>
[0258] Next, a 700.degree. C. heat treatment was performed on thus
obtained tungsten oxide powder for one hour. Consequently, there
was obtained tungsten oxide (WO.sub.3) powder having an average
particle diameter of 45 nm as a diameter converted from a BET
specific surface area (19 m.sup.2/g on average).
(Evaluation of WO.sub.3 Powder)
[0259] A Raman spectroscopic analysis was performed on the WO.sub.3
powder thus obtained in the same way as in Practical Example 1.
Table 6 shows the results of the analysis.
TABLE-US-00006 TABLE 6 First Peak Second Peak Third Peak Fourth
Peak Fifth Peak Peak Peak Peak Peak Peak Peak Peak Peak Peak Peak
Position Intensity I.sub.1 Position Intensity I.sub.2 Position
Intensity I.sub.3 Position Intensity I.sub.4 Position Intensity
I.sub.5 Sample No. (cm.sup.-1) (cps) (cm.sup.-1) (cps) (cm.sup.-1)
(cps) (cm.sup.-1) (cps) (cm.sup.-1) (cps) Examples 16-18 274 5620
717 9126 807 16382 135 3246 934 4
(Preparation of Electrode Material Paste for Batteries)
[0260] Next, a metal oxide coating film made from yttrium oxide was
disposed on thus obtained tungsten oxide (WO.sub.3) powder
(sample). In addition, 95 parts by mass of the tungsten oxide
(WO.sub.3) powder on which the metal oxide coating film was
disposed, 5 parts by mass of magnesium oxide (MgO) powder (68 nm in
average particle diameter) were mixed to prepare a mixed
sample.
[0261] Then, 37 parts by mass of the mixed sample, 5 parts by mass
of ethyl cellulose, and 58 parts by mass of a terpineol solvent
were mixed thereby to prepare electrode material paste for
batteries (paste sample) having a viscosity at 25.degree. C. of
5010 cps.
(Fabrication of Storage Batteries)
[0262] The storage battery 2 illustrated in FIG. 3 was fabricated.
Three types of storage batteries 2 were fabricated as Practical
Examples 16 to 18 by varying the thickness of the spacer resin 56
and the composition of the electrolytic solution.
[0263] First, there was prepared an electricity generation-side
complex 91 in which a transparent conductive film 52 was formed on
one side of the same glass substrate 51a (1.1 mm in thickness and
5.OMEGA./.quadrature. in sheet resistance) as used in Practical
Example 11.
[0264] The paste sample (electrode material paste for batteries)
was printed and coated on a surface of the transparent conductive
film 52 by a screen printing method. The temperature of the glass
substrate 51a coated with this paste was raised from 25.degree. C.
to 450.degree. C. in the atmosphere at a temperature rise rate of
15.degree. C./min using an electric furnace, and then the glass
substrate 51a was calcinated at 500.degree. C. for 40 minutes.
After completion of the calcination, there was formed an
electricity storage layer 83 composed of a porous body formed on
the surface of the transparent conductive film 52 as the result of
the particles of the mixed sample being necking-bonded to one
another. The porous body was 55% in voidage and 50 .mu.m in
thickness.
[0265] Next, a tubular spacer resin 56 the thickness of which in a
thickness direction of the electricity storage layer 83 was 50
.mu.m and in which electrolytic composition inlets were arranged in
two places was disposed so as to surround the periphery of the
electricity storage layer 83. Thereafter, the electrode 54 and the
non-electricity generation-side complex 92 (the same complex as the
one discussed in Practical Example 11) heated to 110.degree. C.
were bonded to each other. The thicknesses of the spacer resin 56
are as shown in Table 7.
[0266] An electrolytic composition (electrolytic solution) 70 was
injected from an electrolytic composition inlet with a syringe, and
the inlet was sealed up with UV-curable resin. Table 7 also shows
the composition of the electrolytic solution. TBP in Table 7 refers
to tertiary butylpyridine.
TABLE-US-00007 TABLE 7 Spacer Electrolytic Solution Electricity
Resin Electrolytic Composition Storage Thickness Organic Solvent
Concentration Capacity Sample No. (.mu.m) Material Material (mol/L)
(C/m.sup.2) Example 16 200 Propyrene Carbonate Lithium Iodide 1.5
8200 Iodine 0.1 TBP 1.0 Example 17 200 .gamma.-Butyrolactone
Lithium Iodide 2.0 10720 Iodine 0.05 TBP 1.0 Example 18 300
.gamma.-Butyrolactone Lithium Iodide 2.0 13510 Iodine 0.05 TBP
1.0
[0267] As the result of the above-described work, there were
obtained the storage batteries according to Practical Examples 16
to 18.
(Evaluation of Storage Batteries)
[0268] The electricity storage capacities of the respective storage
batteries thus obtained were measured in the same way as in
Practical Example 11. Table 7 shows the results of the
measurement.
[0269] As is evident from the results shown in the table, it has
proven that electricity storage capacity is increased further by
improving the necking bondability of electrode materials for
batteries.
[0270] While several embodiments of the present invention have been
described, these embodiments are shown by way of example only and
are not intended to limit the scope of the invention. These novel
embodiments may be carried out in other various ways, and various
omissions, substitutions and modifications may be made therein
without departing from the gist of the invention. It should
therefore be noted that these embodiments and the modifications
thereof fall within the scope or gist of the present invention, as
well as in the scope of the present invention as defined by the
appended claims and equivalents thereof.
REFERENCE SIGNS LIST
[0271] 1: Dye-sensitized solar cell [0272] 1A: First dye-sensitized
solar cell [0273] 1B: Second dye-sensitized solar cell [0274] 2:
Storage battery [0275] 5: Solar cell [0276] 7: Solar cell-storage
battery composite device [0277] 10: TiO.sub.2 (photoelectric
conversion material) [0278] 20: WO.sub.3 (electrode material for
batteries) [0279] 30: Dye [0280] 51, 51a, 51b: Glass substrate
[0281] 52: Transparent conductive film [0282] 53: Pt counter
electrode [0283] 54: Electrode [0284] 55: Mesh-like electrode
[0285] 56: Spacer [0286] 57: Lead wire [0287] 59: Space [0288] 61,
62, 63, 64: Direction of electron flow [0289] 70: Electrolytic
solution (electrolytic composition) [0290] 75: Light [0291] 81:
Electricity generation and storage layer [0292] 82: Electricity
generation layer (power generation layer) [0293] 83: Electricity
storage layer [0294] 91: Electricity generation-side complex [0295]
92: Non-electricity generation-side complex
* * * * *